The regional differences are interesting. But I think time is also a factor.
Growing up in Scotland we had -
Tea the drink at any time possible
Afternoon Tea was what you were served when you went visiting a family friend and you got to sit in the good sittingroom. It was tea, scones, cakes and Orange Barley Water for the kids.
High Tea was a meal you had between 4-7pm out at a bar or sit down chippy. It was fish or scampi, chips, mushy peas, bread and a pot of tea.
Cream Tea, is what my Nana and her pals went for in a naice hotel once a month. Tea, scones, jam and loads of whipped cream. (I'm having flashbacks of the smell of face powder, cream and Embassy cigarettes).
Tea is also dinner, your main evening meal and people used to use both eg. Mums gettin' tea ready so's a've got tae be quick.
Now though…
Afternoon tea or High tea is served in every cafe/bar/hotel as tea or champagne with a load of mini sandwiches and cakes.
None of my kids of their friends use tea for evening meal. They call both lunch and evening meal, dinner.